Synaptic plasticity in the mormyrid electrosensory lobe

The mormyrid electrosensory lateral line lobe (ELL) is one of several diffe rent sensory structures in fish that behave as adaptive sensory processors. These structures generate negative images of predictable features in the s ensory inflow which are added to the actual inflow to minimize the effects of predictable sensory features. The negative images are generated through a process of association between centrally originating predictive signals a nd sensory inputs from the periphery. In vitro studies in the mormyrid ELL show that pairing of parallel fiber input with Naf spikes in postsynaptic c ells results in synaptic depression at the parallel fiber synapses. The syn aptic plasticity observed at the cellular level and the associative process of generating negative images of predicted sensory input at the systems le vel share a number of properties. Both are rapidly established, anti-Hebbia n, reversible, input-specific and tightly restricted in time. These common properties argue strongly that associative depression at the parallel fiber synapse contributes to the adaptive generation of negative images in the m ormyrid ELL.